Low vertebral bone density values in young non-elite female runners

Thirty-five female runners (26.6 +/- 0.9 years, range 17-35) were scheduled for bone mineral density evaluation, using quantitative computed tomography of the lumbar spine. In 17 women with oligo-amenorrhea, vertebral bone mineral density was under the normal range (defined from a control group of 46 sedentary healthy females in the same age range), while it was within the normal range in all runners with regular menses (n = 18). When age classes were considered, all runners aged 17-21 (11/11) were found to have oligo-amenorrhea and low bone mineral density values, the difference in mineral density with the controls of the same age quartile being highly significant (p less than 0.001). Runners from the two youngest age classes (17-21 and 22-26) had started training early after menarche (0.9 +/- 0.6 and 2.5 +/- 1.6 years, respectively). These results show that very young female runners with oligo-amenorrhea may have impressively low bone mineral density values. The possibility that early onset of training, close to menarcheal age, might be a risk factor for low mineral density, deserves further investigation.